Motor Tracts

Question 1

What muscles does the medial corticospinal tract innervate?

Answer 1

Postural (neck, shoulder, trunk) muscles.

10%

Question 2

What muscles does the lateral corticospinal tract innervate?

Answer 2

Limb movements (fractionation).
90%

Question 3

Direct pathway of the corticospinal pathway

Answer 3

Cell bodies arise in cortex.
Axons descend through the posterior limb of the internal capsule.
Continues through the cerebral peduncles, anterior pons, pyramids.
Fibers cross in the pyramids and descends in the lateral column of the SC.
Synapses w/ LMNs in the spinal cord.

Question 4

Where are areas located in the Homunculus?

Answer 4

Medial is LE.
Middle 1/3 is UE.
Lateral 1/3 is Head/neck.

Question 5

Where do the UMNs synapse w/ the LMNs in the spinal cord?

Answer 5

Ventral (anterior) horn

Question 6

Which CNs use the corticobulbar (corticonuclear) tract?

Answer 6

CNs V, VII, IX, X, XI, XII

Question 7

Corticobulbar tract pathway

Answer 7

The exact same as the corticospinal, EXCEPT: it travels through the genu of the internal capsule, not the posterior limb.

Question 8

Organization of the ventral (anterior) horn:

Answer 8

Medial LMNs go to axial/postural ms.
Lateral LMNs go to limb ms.
LMNs innervating extensors lie ventral.
LMNs innervating flexors lie dorsal.

Question 9

Medial LMNs get input from: (5)

Answer 9

Tectospinal tract
Medial vestibulospinal tract
Medial reticulospinal tract
Medial corticospinal tract
Lateral vestibulospinal tract

Question 10

Lateral LMNs get input from: (3)

Answer 10

Rubrospinal tract
Lateral reticospinal tract
Lateral corticospinal tract

Question 11

Do the cranial nerves in the corticobulbar tract stay ipsilateral, contralateral, or BL?

Answer 11

CN V: BL
CN VII: BL of forehead, CL to low face.
CN IX, X, XI: CL
CN XI: IL

Question 12

Lateral vestibulospinal tract

Answer 12

Vestibular nuclei to SC.
IL LMNs innervating postural ms. and extensors.
*opposes gravity

Question 13

Medial vestibulospinal tract

Answer 13

Vestibular nuclei to SC.
To cervical and thoracic levels.
*head movements

Question 14

Medial (pontine) reticulospinal tract

Answer 14

Pontine RF to SC.
IL LMNs innervating postural ms. and extensors.
*postural reflexes

Question 15

Lateral (medullary) reticulospinal tract

Answer 15

Medullary RF to SC.

Facilitates flexor motor neurons and inhibits extensor motor neurons.

Question 16

Rubrospinal tract

Answer 16

Red nucleus (midbrain) to SC.
Innervates UE flexors.

Question 17

Tectospinal tract

Answer 17

Superior colliculus to upper SC.

To neck ms.

Question 18

Symptoms associated with LMN lesions (5)

Answer 18

Flaccid paralysis
Wasting/atrophy
Hyporeflexia
Hypotonia
Fasciculations

Question 19

Symptoms associated with UMN lesions (

Answer 19

Loss of distal extremity strength.
Babinski sign (inverted plantar reflex)
Hypertonia (spasticity, rigidity)
Hyperreflexia

Question 20

Spasticity is indicative of:

Rigidity is indicative of:

Answer 20

Spasticity: UMN lesion
-rate dependent w/ loss of resistance at end of ROM.
Rigidity: basal ganglia disease
-rate independent, constant throughout ROM.

Question 21

LMN damage result in clinical signs where?

Answer 21

IL to the lesion

Question 22

UMN lesions above the medulla will have clinical signs where?

Answer 22

CL to the lesion

Question 23

UMN lesions in the SC will have clinical signs where?

Answer 23

IL to the lesion

Question 24

Decorticate posture is a result of a lesions where?

What’s the posture?

Answer 24

Lesion above red nucleus.

Elbows flexed and arms pronated w/ LE extension.

Question 25

Decerebrate posture is a result of a lesion where?

What’s the posture?

Answer 25

Lesion below red nucleus, but above reticospinal and vestibulospinal nuclei.

UE pronated and in extension as well as the LE.

Question 26

What are all of the deficits when there is a complete transection of the SC? (5)

Answer 26

All sensation lost 1-2 segments below lesion.
Bladder/bowel control are lost.
Spinal shock.
UMN signs below lesion.
LMN signs at the level of lesion.

Question 27

What are the deficits when there is a hemisection of the SC?

Answer 27

Loss of pain and temperature from CL side of body (ALS).
Loss of discriminative touch and proprioception on IL side (PCMLS).
LMN signs at level of lesion.
UMN signs IL to lesion.

Brown-Sequard syndrome

Question 28

Spyringomyelia affects:

Answer 28

First pain and temp (hits AWC first).
Cape and/or shawl pattern.
MAY have LMN signs at ventral horns.
MAY have UMN signs if lateral CST is affected.

Question 29

Anterior cord syndrome

Answer 29

Damage/compression to anteriro part of SC.
Loss of IL motor from LCST and LMN.
Loss of CL ALS (pain and temp).

Question 30

Central cord syndrome

Answer 30

AWC is hit –> BL loss of pain and temp.

If it hits anterior horns, there might be LMN problems.

Question 31

Medial medullary syndrome

Arterial supply to medial medulla?

Answer 31

Hits pyramids, ML, and hypoglossal nucleus.
Pyramids: CL UMN sx.
ML: CL loss of PCML.
HN: IL protruding tongue.

Arterial supply: anterior spinal a.

Question 32

Lateral medullary syndrome

Arterial supply?

Answer 32

Hits ALS, spinothalamic nucleus/tract, nucleus ambiguus.
ALS: CL loss of pain and temp.
ST N/T: IL loss of pain and temp to face.
Nucleus ambiguus: voice problems, dysphagia, CN IX, X problems.

Arterial supply: PICA

Question 33

Central seven palsy

Answer 33

Lesion of corticobulbar tract w/ CN VII.
Upper facial muscles can function OK because fibers from both sides contirbute.
Muscles of lower face are controlled by CL hemisphere.

Lesion on left will have right-sided lower face paralysis.

Question 34

Weber’s syndrome

Answer 34

Blood loss to parts of midbrain (CST, CBT, CN III).
CST: CL UMN sx.
CBT: CL low face droop.
CN III: down and out eye, dilated pupil.

Question 35

Amyotrophic lateral sclerosis (ALS)

Answer 35

Destroys only somatic neurons.
Leads to UMN sx.
CN involvement leads to problems breathing, swallowing, speaking.